About a year ago, model Susan McNabb was relaxing in her Los Angeles home when her husband looked up from his laptop-surfing and mentioned a gossip item he thought she’d find interesting. It seemed her longtime, long-ago boyfriend, Jerry Seinfeld, was planning a new TV project called “The Marriage Ref,” yet another reality-style show, this one dealing with the marital squabbles of real-life couples.

“Seinfeld? Marriage counseling? WHAT?!” exclaimed McNabb.

She couldn’t believe what she was hearing, and recalls thinking, “It’s ironic that the man who avoided the mere mention of marriage in my presence for years has now grown into a full-on television-show-producing expert on the subject of marriage and marital problems. And after years of my consciously avoiding any and all news of Jerry Seinfeld, here we go again.”

The new Seinfeld project “brought up a lot of old feelings about Jerry that I’d worked long and hard to bury,” asserts McNabb. But instead of “Seinfeld” sitcom-style kvetching, the 50-year-old TV-commercial and print model found a way to cope with her demons.

“I sat down at my computer and started writing everything down. I felt like I was purging those old feelings, a form of much needed therapy. The good news is I probably saved a fortune in psychotherapy.” The bad news for Seinfeld is that he may soon find himself fictionally portrayed between the covers of what the author says is a “juicy, sexy, introspective, and poignant” chick-lit novel called, “It Seemed Funny at the Time,” and which McNabb is pitching as “Bridget Jones meets Mr. Comedy.” Says McNabb, “I didn’t want to write a kiss-and-tell, so I made it a novel.” With the much ballyhooed “The Marriage Ref” set to debut on March 4 on NBC, McNabb is finishing her roman à clef dealing mostly with her turbulent eight-year relationship with a successful stand-up whom she hoped to marry.

But as any Seinfeldologist knows, that union never happened.

Instead, the 55-year-old iconic funnyman — who once suffered from commitment-phobia extremus — celebrated his 10th wedding anniversary last Christmas Day with Jessica, the 38- year-old mother of his three children, Shepherd, Julian, and Sascha.

Although their union was born out of scandal (Jessica left her newlywed hubby, Eric Nederlander, for Seinfeld just days after returning from her honeymoon in Italy), the Seinfelds are said to be happy together.

“I wish them a mazel tov,” intones Rabbi Charles A. Klein.

“I hope [their marriage] lasts for a long time. That was my prayer under the chuppah when I married them, and remains my prayer for them for the rest of their lives.”

Nevertheless, an argument between the Seinfelds in their Central Park apartment is said to have sparked the original concept for “The Marriage Ref.” A friend of Jessica’s was present, but when things started getting heated, she thought it wise to take her leave. But Jerry said, No, stay, referee this bout, and tell us who gets the Golden Gloves. Jessica, a sharp cookie herself — she recently wrote a best-selling cookbook — thought, “Hey, this could be a TV show.” And before you could say “NEWMAN!!!” Seinfeld pitched the idea and got the green light.

Meanwhile, back in LA, Susan McNabb, struck by the irony of Seinfeld’s new show, was pounding out her novel.

Her nonfiction relationship with Seinfeld began in spring 1985 when the cute, 5-8 then-lingerie model and aspiring actress with a 34C-23-33 figure met the skinny comic at a Beverly Hills party, several days after he turned 33. (When he was first developing “Seinfeld,” a character named “Susan” was written into the script — named for McNabb — but it was later dropped, she says.)

Today, McNabb appears in commercials and ads for banks and businesses because, “I’m not the slim, trim 25-year-old I was when I was with Jerry. At 38, I stopped coloring my hair and was prematurely gray, so I jumped directly from the babe category to a more womanly look.”

While back in her Seinfeld days, McNabb dressed and looked like a hot “Robert Palmer Girl,” she actually came from a conservative Christian background. And although she had a busy modeling career, she also had a degree from the University of Tennessee, where she was an English lit major.

The message of McNabb’s book, she says, “is to follow your heart and be true to yourself. The story shows some of the unique challenges of dating men in the public eye, and what an odd phenomenon fame is.”

Three major obstacles stood in the way of matrimony with Seinfeld, McNabb contends: His burgeoning career, religion, and his dire fear of commitment, which was so severe that they never lived together, although he did entrust her with the keys to his West Hollywood condo so she could take care of his personal business while he was on the road.

“Even though I had always felt that I’d prefer marriage before cohabitation, I did hope that we would live together,” she told The Post.

“I saw many of my friends using that as a step towards marriage, and so I hoped for the same with Jerry.

“But I knew that he gave 100 percent of himself to his work. It was important for him to not have other commitments that required his attention. Unfortunately, that’s when I was in his life,” she observes.

The couple had a number of lovers’ spats and splits — when he dated other women, and she went out with other men, including two other famous comics who will surface in her novel (and she declines to identify publicly). Like “The Marriage Ref,” which Seinfeld is co-producing, he also stage-managed his on-and-off relationship with McNabb solely on his terms, she claims.

“Jerry and I broke up eight times in eight years,” she says. “It got to the point where all I had to do was say a word like ‘relationship,’ and I’d get the breakup speech. After a while, I knew it by heart; it was always essentially the same. He didn’t want to be in a committed relationship. Well, I did. While every breakup was skillfully engineered by Jerry, he was also in charge of getting us back together. All I really had to do was say yes — and I always did. We actually got really good at it. If we planned it right, I could still make my morning auditions and schedule the tearful angst for after dinner.”

Regarding their religious differences, it was a touchy subject that was discussed.

“Jerry was not what I would call very religious. But I made it clear to him that I would be willing to consider converting to Judaism if we were to get married. Did the fact that I’m not Jewish factor in to why he didn’t want to marry me? I really don’t know. I can only say that for me, it wasn’t an issue.” But it clearly was an issue for Betty Seinfeld, the comic’s archetypical Jewish mother, a busty little dynamo of Syrian descent, who had one strict rule about marriage for Jerry: that he marry a nice Jewish girl, and not even a convert to the faith. Without really knowing it, McNabb didn’t have a chance.

When Seinfeld took McNabb home to meet the family in Massapequa, LI, she says she never felt a negative vibe.

“If Betty had a problem with my not being Jewish, I certainly was never aware of it. She could not have been sweeter to me. I met Betty several times. She was wonderful. I loved her.” Despite all of Seinfeld’s issues, McNabb was certain that he would eventually be the marrying kind, and she knew he wanted to be a daddy. To her shock and amazement, he made that abundantly clear to her long before their breakup.

“He asked me at one point to have a baby with him,” she says, “but even today I’m not sure how serious he really was. I told him I wanted to be married before I had children.

“I knew he’d make a great father, though. Jerry takes care of the people and things in his life, and I knew children would be no exception. I’d bet he keeps those kids giggling all the time.” Looking back on her Seinfeld years as she works on her novel, McNabb believes that he not only desired a romantic relationship, but also a mother-figure as a wife, a role she says she played, caring for everything from his laundry to his banking, while he was on the road with his act.

People who know the Seinfelds today say he has that kind of relationship with his wife. “Jessica’s the ultimate Palm Pilot,” says one close observer.

The final act of the Seinfeld-McNabb rollercoaster relationship was played out not face-to-face, but on the phone sometime in 1993. It’s a scene McNabb has never forgotten.

“We were just having a normal conversation until I brought up the dangerously taboo subject of marriage,” she recounts. “I held my breath and asked, ‘Do you think we’ll ever get married?’ And Jerry’s answer was a quick and emphatic, ‘No.’ I was amazed that he didn’t even consider it for 10 seconds. And he seemed shocked that I was shocked with his response, and honestly, I was. Way to make a girl feel special there, Jer!

“He innocently asked what he’d done that would lead me to believe that he would ever marry me. In one of the few times I ever raised my voice to him, I said, ‘Oh, I don’t know, maybe the fact that you’ve been chasing my ass for eight years.’ But that line didn’t sound quite as cool punctuated by my sobs.”

In any case, her eight years of love and angst with America’s favorite comic was over, and McNabb learned a big lesson: that being involved with a comedian isn’t always ha-ha. She fell into what she now calls “post-traumatic Seinfeld breakup syndrome.”

Its main symptom? “I cried a lot,” she recalls.

“After a while, I started dating the men who seemed to be perpetually on my waiting list, but comedians were definitely off-limits for me. I didn’t want to repeat past mistakes that I’d already repeated eight times with Jerry. Admittedly, I was a little slow to catch on with him.”

By the time McNabb reached the big mid-4-0 mark, she was convinced that she was going to be a spinster, albeit one with a lot of dates, but no one of any great interest. She had her own home, a secure career as a model, wonderful friends and family, and a houseful of dogs and cats that she had rescued. Two things she didn’t do: watch reruns of “Seinfeld,” and read anything about him. But at the point that McNabb declared to herself that she was happy to be alone, self-sufficient and independent, along came a new man — Paul McMinn, a senior sales executive.

“I got an e-mail out of the blue from a guy I went to high school with. He found me through the Internet, when he was looking for an old flame of his who was a girlfriend of mine in school. We were engaged in three months, and walked down the aisle in five more. It might have taken me a little longer than most, but I finally did find the right guy. The commitment that had always seemed so unreachable for me with Jerry was suddenly as easy as pie.

“My life now is good and feels like the ‘normal’ one that I always wanted. Let’s face it, had Jerry granted me my wish and married me, the last thing my life would be right now is normal, so in many ways, he did me a favor. Yes, he broke my heart eight times, but he also became a part of my personal history for which I’m really grateful. I have some great memories and unusual experiences that I’ll never forget. And my book will soon be finished and once it’s published I can share the fun and games with everyone else.”

Jerry Oppenheimer is the author of 10 biographies including 2002’s “Seinfeld: The Making of an American Icon.”